A Bright Idea

Laser lab:
Erik Spahr (right) and Gunter Luepke make an adjustment as they set up an infrared laser array in their old lab in the basement of Small Hall.

Your first fuel cell-powered car just moved a little closer

by Joseph McClain
| May 10, 2010

A pair of researchers may have
brought the affordable fuel
cell-powered car a step or two closer to reality.

Gunter
Luepke and Erik Spahr are working to perfect their invention, a process
designed to reduce the operating temperature of one type of fuel cell. Cooler
operating temperatures remove some of the barriers to fuel-cell use.

Fuel cells
work by converting chemical energy into electricity. The chemical energy comes
from a fuel that could be hydrogen, or hydrocarbons or fossil fuels, said
Luepke, professor of applied science at William & Mary. But the most common
class of fuel cells, proton-exchange membrane (PEM) cells, run only on hydrogen.

Luepke and
Spahr, a Ph.D. student in applied science, are focusing on solid-oxide cells, a
less-common technology. When it comes to potential for automobiles or other
portable uses, each fuel-cell technology comes with its own set of yet-unsolved
problems. Problems with the PEM cells, Luepke said, center around their only
fuel: hydrogen. Production costs for hydrogen are high and storage of the gas
poses its own set of problems. Not least, he said, is the virtual lack of
hydrogen fueling systems.

On the
other hand, solid-oxide fuel cells are more versatile, being able to run on
hydrogen or just about any hydrocarbon—propane, butane, many biofuels and even
gasoline-readily available fuels.

Heat's the problem

The
problem is that the solid-oxide fuel cells have to run at very high
temperatures—about 600 to 1,000 degrees Celsius, Luepke explained. High
operating temperatures requires a long start-up time. You turn them on and it
takes an hour for them to reach operating temperature.

The high
operating temperature of solid-oxide fuel cells has other implications.
Hot-running fuel cells are subject to degradation, he said, which is aggravated
by turning the cell off and on.

"In a car,
you don't want to have to run the fuel cell all the time, because you will burn
up the fuel," he said. "For a car or any portable application, you would like
to have short start-up times. You want to turn it on and in a few seconds, have
it up and running. That requires that you reduce the operating temperature."

Today's
solid-oxide fuel cells run hot to facilitate the chemistry, Spahr said. The
anode breaks down the fuel into hydrogen ions and electrons. Then, the ions
diffuse through the solid-oxide electrolyte, while the electrons travel around
the outside of the cell, and as Luepke says, do all the work, or make
electricity.

The
electrons can't get to work until the ions pass through the electrolyte,
completing the chemical reaction. "How fast the ions can move through the
material is a limiting factor," Spahr explained. "Solid-oxide fuel cells must
be run at high temperatures in order for the ions to move through the
electrolyte with relative ease."

Replacing heat with light

Heat
speeds up the ion passage, but Luepke and Spahr have found a way to get the
same effect optically. They use infrared light to excite the hydrogen, which
then becomes mobile, allowing the hydrogen ions to complete their trip through
the electrolyte more easily. In the lab, they've shown the effect of the
infrared light to increase the ion conductivity by seven to nine orders of
magnitude.

It's a
huge effect, Luepke said, and that corresponds to a reduction in operating
temperature of 200 to 300 degrees Celsius. Instead of running at 600 to 800
degrees, the enhanced cells could run much cooler.

Their
invention could put solid-oxide fuel cells back into consideration for
automotive and other portable uses. Cooler operating temperatures would make
solid-oxide fuel cells less expensive to manufacture. Luepke explained that
their invention would allow cells to be constructed with steel electrodes,
rather than using platinum, as required in current solid-oxide cells.

"It would
also decrease the startup time, which is a big issue for automotive
applications," Spahr said. "If you can make these hydrogen ions mobile
optically, startup time will be much quicker. With our invention, startup will
probably drop from hours to minutes—possibly seconds."

Luepke
likes to compare the process to the operation of a microwave oven. A
conventional oven, he explains, heats up the entire oven space, including the
food. A microwave, by comparison, heats only the water molecules in the food.
"Here, we're using infrared radiation to heat up just the hydrogen," he said.

Spahr and
Luepke say their invention also could work the other way, enhancing the
efficiency of the production and storage of hydrogen, which can be used in
solid-oxide or PEM fuel cells.

"Hydrogen
production is just a fuel cell in reverse," Spahr explained. "You apply an
electric current to a fuel like methane and the process re-forms it and you get
hydrogen out of one end. There's a similar process for making hydrogen from
water—water splitting."

Their work
has been funded for the past 12 years by the National Science Foundation. Now,
Luepke and Spahr are ready to take their work to the next level. They have
started a company called Phenom—the name is a kind of acronym for
photo-enhanced oxide membrane. Working with Jason McDevitt, the College's
director of technology transfer, they've filed for patent protection for their
invention.

"This
startup company has great potential," McDevitt said. "It's a tremendously
innovative approach that could provide a solution to a very important problem.
Obviously, development of a commercial product is a long way off, with many
challenges to overcome, but we are very excited about the prospects for this
technology."

Phenom seeks funding

As Phenom, Luepke and Spahr are seeking
support from the U.S. Small Business Administration Office of Technology.
They've applied for Small Business Innovation Research (SBIR) funding of $1
million for three years to continue their investigation. They've done their
work so far using low-power infrared lasers in their lab in the basement of
Small Hall. With the SBIR funding, they will move their investigation to the
Free Electron Laser at the Thomas Jefferson National Accelerator Facility (the
J-Lab) in Newport News.

"At the J-Lab, we'll be
able to use the high-powered laser to sort things out and the project should
move along more quickly," Luepke said. "While a commercial product is years
away, it is possible that the first fuel-cell car you buy may be based on this
technology developed at the College of William and Mary."